Drain a paediatric skin abscess — OSCE

A previously well 6-year-old presents with a four-day history of a tender, red, domed lump on the right thigh. The temperature is 37.2°C, the lump is 4 cm across and fluctuant with a central pointing pustule, and there is surrounding cellulitis extending about 3 cm beyond the margin. The child weighs 22 kg and is anxious but cooperative. The team has decided to drain the abscess in the treatment room. You are the paediatric registrar asked to assess the child and outline how you would perform the procedure safely.